Incinerator apparatus

ABSTRACT

A system for incinerating municipal waste and refuse wherein a movable grate serves as the sole means for controlling the rate at which the refuse traverses the incinerator. The movable grate preferably comprises a plurality of rotary grate members driven so that their upper surfaces advance the refuse while their lower sides carry the ash away from the burning chamber.

[ Aug. 22, 1972 finite States tent MenigatKremer........................ Gunson [54] INCINERATOR APPARATUS3,469,544 9/1969 [72] Inventor: Richard Menigat, Dietzenbach, Ger-3038421 6/1962 many [73] Assignee: MetallgesellschaftAktiengesellschaft,

FOREIGN PATENTS OR APPLICATIONS Great 10/35 Frankfurt am Main, GermanyAug. 27, 1970 ABSTRACT [22] Filed:

[21] Appl.No.:67,378

[30] Foreign Application Priority Data Aug. 29, 1969 A system forincinerating municipal waste and refuse wherein a movable grate servesas the sole means for Germany..........P 19 43 855.2

controlling the rate at which the refuse traverses the incinerator. Themovable grate preferably comprises a plurality of rotary grate membersdriven so that their [52] US. Cl. R, 110/40 R [51] Int. 5/00 [58] Fieldof Search.........................110/8, 18, 35, 40 pp surfaces advancethe refuse while ei lower sides carry the ash away from the burningchamber.

9 Claims, 8 Drawing References Cited UNITED STATES PATENTS 3,031,9825/1962 Gordon et 10/40 V PATENTEmusze m2 3.687; 094

SHEET 1 [IF 5 In ven tor Richarcl Menigaf jqttomey PATENIEDwszs m2 SHEET2 BF 5 QZQN 9 5 M mc PATENTEDAUBZQ m2 3; e87; 094

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l RTYYII R In van (or; Richard Men/gar {RNA Attorney PATENTEDMIS29 19123587094 Richard Men/gar PATENTEBwszs 1912 SHEET 5 BF 5 Inventor,Richard, Men/gar BY R Attorney INCINERATOR APPARATUS l. FIELD OF THEINVENTION 2. BACKGROUND OF THE INVENTION Massive incinerator systemshave been proposed heretofore for large municipalities and metropolitanareas to burn the refuse and garbage accumulated during refusecollection by truck systems and the like. Such incinerators may havetraveling grates or the like carrying the refuse from the input side tothe output side of the combustion chamber in which the garbage or refuseis consumed by fire, in part as a result of selfburning and in part bythe combustion of fuels which may be introduced into the chamber throughburners or can be mixed with the refuse. However, for small cities andmunicipalities, large-size incinerator systems are not suitable because,on the one hand, insufficient refuse is collected to operate theincinerator efficiently and because, on the other hand, the high capitalcosts of such systems are prohibitively expensive for smallmunicipalities having a low tax base.

3. OBJECTS OF THE INVENTION It is the principal object of the presentinvention to provide an improved incinerating method and system,especially intended for small or moderate sized municipalities andinstitutions which will avoid the disadvantages of large incineratorinstallations and yet provide efficient and economical destruction ofrefuse and garbage.

I may also mention the fact-that incinerator systems have been proposedheretofore with both traveling grates and crane-type transfer of therefuse into the combustion chamber, such systems being suitable only forlarge municipalities and governmental units. It has also been proposedto provide small incinerator units in which an inclined shaft feeds therefuse to the combustion chamber by gravity, combustion taking place atthe bottom of the shaft. The latter systems have proved to beineffective since the movement of the refuse to be incinerated is afunction of its composition which may vary within a wide range andbecause the nature of the packing of the refuse and its tendency toprevent the passage of air at least through lower portions under theweight of a column of refuse thereabove, prevents efficient burning. Thesmall and moderate municipalities, therefore, have been faced with achoice between inefficient and often ineffective incinerators of smallsize or larger installations which are likewise of low efficiency andhigh operating cost, but are prohibitively expensive.

It has, moreover, been proposed to treat the refuse, before it isintroduced into the smaller incinerators of the character described, bycomminution or homogenization to eliminate variations in the packing andoverall texture of the refuse and permit the combustion thereof in amore uniform manner. Comminution, shredding and like devices, however,are of high cost, are prone to breakdown and introduce a further step inthe refuse-disposal chain which substantially complicates the latter.

It is, therefore, another object of this invention to provide animproved incinerator, especially for smallsize or moderate-size towns,cities or other municipalities and governmental units, which avoids theaforedescribed disadvantages and affords efficient combustion of refuseand garbage of the type conventionally collected from such governmentalunits and nevertheless permits efficient burning thereof at relativelylow capital cost and operating cost.

4. SUMMARY OF THE INVENTION These objects and others which will becomeapparent hereinafter are attained, in accordance with the presentinvention, with an incinerator system having a downwardly and forwardlyinclined shaft into which the refuse or garbage is fed at the top of theshaft, while the advance of the refuse through the combustion chamber iseffected solely by a moving-grate system. The passage of the refuse fromits storage pile through the incinerator is, therefore, determinedexclusively by the movement of the grate.

According to a more specific feature of this invention, the incineratorinstallation comprises a collection and storage compartment formed withan upwardly and forwardly inclined conveyor which lifts the refuse tothe mouth of the previously mentioned downwardly inclined input shaft orcolumn, the lower end of which overlies or communicates with the movablegrate whose operation regulates the advance of the refuse through thefurnace. The moving grate of the present invention comprises an array ofgenerally parallel and interleaved roller grates which may have coplanaraxes and may be tangent along their upper surfaces to a commonhorizontal plane, the grates all being driven in the same sense so thattheir upper surfaces move as a forward direction and carry the refusefrom one grate roller or drum to the next. The roller grates are,according to the invention, provided with angularly equispacedarc-segmental ribs which are received between the ribs of the adjoininggrate roller or drum and which serve to carry the refuse across thefloor of the combustion chamber. Furthermore, the codirectionally movinglower surfaces of the roller grates sweep above the floor of the furnacein the opposite direction to carry away the ash.

It has been found to be advantageous to increase the speed of the rotarygrate members at the downstream side of the array, advantageously in astepped or progressive manner so that each succeeding grate travels at aslightly higher speed than the preceding grate and to constitute therotary grate members as hollow shafts or with hollow shafts tofacilitate cooling.

5. DESCRIPTION OF THE DRAWING The above and other objects, features andadvantages of the present invention will become more readily apparentfrom the following description, reference being made to the accompanyingdrawing in which:

FIG. 1 is a diagrammatic vertical cross sectional view of an incineratorinstallation embodying the present invention;

FIG. 2 is a vertical section drawn to an enlarged scale of a detail ofthe system of FIG. 1;

FIG. 3 is a cross section diagrammatically illustrating the junctionbetween two such drums according to the invention.

FIG. 4 is an axial cross section through one of the drums, portionsthereof being omitted;

FIG. 5 is a side-elevational view of one of the members of this grate;

FIG. 6 is a side view thereof;

FIG. 7 is a section taken along the line VII-VII of FIG. 5; and

FIG. 8 is a diagram illustrating the distribution of air to the hollowshaft of a rotary grate member according to the invention.

6. SPECIFIC DESCRIPTION In FIG. 1, I have shown an overall view of aninstallation for incinerating refuse and garbage and particularly anapparatus for use in small municipalities which cannot economicallyprovide large-scale installations.

The installation comprises a storage bunker or chamber 1 which may belocated below grate 1a and can be defined by an upwardly inclined walllb of concrete which includes an acute angle B with the floor 1c of thisbunker. At the upper edge of this wall 1b, there is provided a curb 1dagainst which a sanitation refuse collection or dump truck 1e may bebacked up to unload the refuse 1 f. Along the floor 10, there isprovided a conveyor arrangement 2 whose lower or upstream end 2a islocated beneath the wall lb while the upper end of the conveyoroverhangs at 2b, the shaft or column 20 of the incinerator 4. Thiscolumn which is inclined downwardly and forwardly, terminates in thecombustion chamber 4a of the incinerator which has a floor 411 alongwhich an array 5 of grate rollers 5a 5e extends. These grate rollers areshown in detail in FIG. 2 and FIGS. 5-7.

At the downstream end of this array there is provided an outlet 7a atwhich noncombustibles are discharged as represented at 7. Ash, fallingbetween the grate rollers 5a 5e, collects on the floor 4b and is scrapedto an outlet 8a at which ash is discharged as represented at 8. Thefurnace 4 is provided with an outlet 40 at the downstream end forconduction of waste gases from the furnace. The outlet 40 communicateswith a heat exchanger 9, and a dust-removal and gas-cleaning apparatus11 16 of conventional type. The gas can, therefore, flow through awasher 12 of the multicyclone type in which nozzles 12a and 12bdischarge washwater from a line 13 into the gas, the particles of sludgebeing collected at 12c and 12d and being led from the system at 13. Ablower 14 has its suction side connected to the washer I2 and passes thewaste gases to a stack 16 via an electrostatic filter 15, the solids ofwhich are washed and returned to the line 13a as represented at a. Theheat exchanger 9 serves to preheat the combustion air as will beapparent hereinafter, the air being fed via a manifold a to the furnacethrough the roller grates 5a See.

The heart of the apparatus of the present invention is, of course, theimproved grate arrangement represented at 5. As can be seen from FIG. 4,each of the grate rollers is journaled in a pair of bearings viarespective shaft portions 19a and 1%, one bearing assembly beingrepresented diagrammatically at 190. The

shaft 1% is, in addition to being journaled in a bearing assembly notshown, provided with a splined or polygonal shaft which can be coupledto the drive motor for rotation of the rollers at adjustable speeds. Anyconventional adjustable speed transmission may be used for this purpose.The drives of the various rollers 5a 5e, however, are controlled so thateach downstream roller 5b, 50 etc. operates at a faster speed than thepreceding upstream roller 5a, 5b etc.

Furthermore, as can be seen from FIG. 2, all of the rollers 5a 5e arerotated in the same sense (counterclockwise as represented by arrows D)to convey the refuse at f from below the column or shaft 2c (FIG. 2)across the floor 4b of the furnace. The first rotary grate drum 50,therefore, is located beneath the pile of refuse in column 2c and servesas the feed means for determining the rate at which the refuse is drawnfrom the column and carried across the furnace.

FIGS. 4 7 illustrate in somewhat greater detail the grate rollersaccording to this invention. It will be apparent from FIG. 4, forexample, that each roller 50 5e comprises a hollow shaft 19 carrying aplurality of axially offset star-shaped grate disks 18 having teeth 17angularly equispaced about the periphery of each disk and of circulararc-segmental shape. As can be seen from FIG. 3, the teeth of the disks1' 6', flanked by end pieces E and F, engage between the teeth of thestar-shaped disks I" '7" so that slight clearances G are providedbetween the rollers to permit ash to fall as flydust to the floor lb(arrows I-l). Hence the upper surfaces of all of the drums move to theleft (FIG. 2) to carry the refuse thereacross while the interfitting orinterleaved arrangement of the drums intensively agitates the layer L ofrefuse transported across the grate. Since the upstream drums 5a, 5brotate at slower speeds than the drums 5c and 5d downstream thereof andthe latter drums operate at a slower speed than the drum 5e, the initialdrying of the refuse along the drums 5a and 5b is carried out with arelatively long residence time while combustion in the zone of grates 5cand 5a is accompanied by increased agitation of the refuse, and thecooling grate Se is highly efficient as a result of the high speed andseparation of the residue of the refuse.

Referring now to FIGS. 5 7, it will be seen that the circular arcsegments 17 have a generally trapezoidal configuration in the sense thatthe arc length S of their inner edges is less than the arc length s oftheir outer edge so that the teeth 17 include angles a which may rangebetween and 120 at their leading and trailing edges 17a and 17brespectively. The edges 17a, 17b etc. are defined between flanks 2bwhich include angles 7 of 60 to with one another. The angular extent ofeach tooth will, of course, depend upon the number of teeth inaccordance with the relationship to 360]N where N is the number of teethemployed. Preferably, N ranges between 4 and 12 and, in the embodimentillustrated in FIGS. 5 7 N 8 so that m 45.

The hollow shaft 19 has an outer chamber 19d which communicates with theinterior 17c of each of the disks 18. The teeth 17 thereof are providedwith openings 17d releasing the combustion air into the furnace. Asshown in FIG; 7, each of the teeth 17 has a pair of flanks 17d and 17fspaced inwardly from the lateral faces 17g and l7h of the disk and acylindrical surface l7i. The flanks 17e, 17f and the surface 171' areall provided with openings 17d as described. Furthermore, the shoulder17j and 17k adjoining the flank 17e and 17f, are provided with opening17d. Internally, each of the disks 17 may be subdivided by partitions18a extending along radii of the drum so that compartments 1817 betweensuch partitions register with respective chambers 21a of the hollowshaft 19. The latter is subdivided by similar partitions 21b into thecompartments 21a and is formed with openings 210 along its circumferenceto register with the chambers 18b. At its lefthand end (FIGS. 4 and 8),the shaft 19 is surrounded by a fluid-distribution hood 21 into whichthe combustion air, preheated in heat exchanger 9, is fed at 21d. Alongthe underside of this hood 21, there is provided a shield 2le with seals21f preventing the entry of air into the chambers 21a of the lower halfof the shaft. The remaining chambers, however, receive the air asrepresented by the arrows M and distributed to the star-shaped disks 18as previously described. The combustion air, therefore, serves to coolthe hollow shaft and the individual elements 18 and the latter have thedual function of advancing the refuse and distributing the combustionair uniformly to the latter. The air emerging from the teeth of thestar-shaped elements 18, moreover, loosens the refuse carried by therotary grates and facilitates transport thereof.

As indicated, the teeth 17 moving to the right along the lower side ofeach of the rotary grates 5a 5e entrain the ash to the outlet 8a whichmay be provided with a water-cooled worm for conveying the ash away fromthe incinerator. At the downstream end of the array of rotary grates,there is provided a comb 22, the teeth of which fit between the teeth ofthe last grate 5e to dislodge any uncombusted residue. This residue isgenerally metal or glass which can be collected separately from the ashwhere, for example, recovery of valuable components (e. g. metal scrap)is desired. In operation, the combustion air introduced into the rotarygrates 5a Se is heated to about 400 C in the heat exchanger 9.

Referring again to FIG. 1, l have shown at 6 nozzles for introducingfresh air into the furnace chamber at an intermediate location along itslength to bring the waste gases to the most effective temperature fordust separation. The conveyor 2 may be provided with flight forentraining the refuse as shown at 2d in FIG. 1 and is preferablycomposed of steel plates. Furthermore, means may be provided at the endof the conveyor as shown at 2e for limiting the height of the layer ofrefuse carried by this conveyor into the column 2e and, indeed,photoelectric means may be provided as represented at 2f to control theconveyor in response to the height of refuse in the column 20. A suctionarrangement maintains a constant reduced pressure within the furnace toprevent the outflow of waste gases through the inlet column or shaftand, when further refuse is not to be supplied to the system, thiscolumn may be closed via a vertically moving door 3.

The improvement described and illustrated is believed to admit of manymodification within the ability of persons skilled in the art, all suchmodifications being considered within the spirit and scope of theinvention except as limited by the appended claims.

lclaim: 1. A refuse incinerator, comprising housing means forming anincinerator chamber having a downwardly extending inlet column at oneside thereof; and a moving grate extending along the bottom of saidchamber from said column and exclusively controlling the rate at whichrefuse is fed to and through said chamber, said moving grate comprisingan array of interleaved rotarygrate drums all rotated in the same sense,said drums being driven at progressively higher speeds in the downstreamdirection.

2. A refuse incinerator comprising housing means forming an incineratorchamber having a downwardly extending inlet column at one side thereof;and a moving grate extending along the bottom of said chamber from saidcolumn and exclusively controlling the rate at which refuse is fed toand through said chamber, said moving grate comprising an array ofinterleaved rotarygrate drums all rotated in the same sense, said drumsbeing formed with axially offset star-shaped disks each provided with aplurality of angularly offset teeth, the teeth of one drum beingreceived between the teeth of a pair of disks of an adjoining drum.

3. The refuse incinerator defined in claim 2 wherein said drums eachinclude a hollow shaft carrying the respective disks, said disks beingprovided with apertures, said incinerator comprising means fordistributing combustion air through said shaft to said disks fordischarge through said apertures.

4. The refuse incinerator defined in claim 3 wherein each shaft and therespective disks are provided with generally radial partitions toconfine the discharge of combustion air from said disks into saidchamber to the upper portions only of each drum.

5. The refuse incinerator defined in claim 4 wherein said drums lie in ahorizontal plane.

6. The refuse incinerator defined in claim 5, further comprising anupwardly inclined conveyor leading to the top of said column fordischarging refuse into the latter.

7. The refuse incinerator defined in claim 6, further comprising meansat the upstream side of said array for collecting ash.

8. The refuse incinerator defined in claim 2 wherein said drums aredriven at progressively higher speeds in the downstream direction.

9. The refuse incinerator defined in claim 2 wherein said array of drumsincludes an inlet drum beneath said column and operated at a speedcontrolling the rate at which the refuse is fed to and through saidchamber.

1. A refuse incinerator, comprising housing means forming an incineratorchamber having a downwardly extending inlet column at one side thereof;and a moving grate extending along the bottom of said chamber from saidcolumn and exclusively controlling the rate at which refuse is fed toand through said chamber, said moving grate comprising an array ofinterleaved rotary-grate drums all rotated in the same sense, said drumsbeing driven at progressively higher speeds in the downstream direction.2. A refuse incinerator comprising housing means forming an incineratorchamber having a downwardly extending inlet column at one side thereof;and a moving grate extending along the bottom of said chamber from saidcolumn and exclusively controlling the rate at which refuse is fed toand through said chamber, said moving grate comprising an array ofinterleaved rotary-grate drums all rotated in the same sense, said drumsbeing formed with axially offset star-shaped disks each provided with aplurality of angularly offset teeth, the teeth of one drum beingreceived between the teeth of a pair of disks of an adjoining drum. 3.The refuse incinerator defined in claim 2 wherein said drums eachinclude a hollow shaft carrying the respective disks, said disks beingprovided with apertures, said incinerator comprising means fordistributing combustion air through said shaft to said disks fordischarge through said apertures.
 4. The refuse incinerator defined inclaim 3 wherein each shaft and the respective disks are provided withgenerally radial partitions to confine the discharge of combustion airfrom said disks into said chamber to the upper portions only of eachdrum.
 5. The refuse incinerator defined in claim 4 wherein said drumslie in a horizontal plane.
 6. The refuse incinerator defined in claim 5,further Comprising an upwardly inclined conveyor leading to the top ofsaid column for discharging refuse into the latter.
 7. The refuseincinerator defined in claim 6, further comprising means at the upstreamside of said array for collecting ash.
 8. The refuse incinerator definedin claim 2 wherein said drums are driven at progressively higher speedsin the downstream direction.
 9. The refuse incinerator defined in claim2 wherein said array of drums includes an inlet drum beneath said columnand operated at a speed controlling the rate at which the refuse is fedto and through said chamber.